What do Bayesian methods offer population forecasters?

The Bayesian approach has a number of attractive properties for probabilistic forecasting. In this paper, we apply Bayesian time series models to obtain future population estimates with uncertainty for England and Wales. To account for heterogeneity found in the historical data, we add parameters to represent the stochastic volatility in the error terms. Uncertainty in model choice is incorporated through Bayesian model averaging techniques. The resulting predictive distributions from Bayesian forecasting models have two main advantages over those obtained using traditional stochastic models. Firstly, data and uncertainties in the parameters and model choice are explicitly included using probability distributions. As a result, more realistic probabilistic population forecasts can be obtained. Second, Bayesian models formally allow the incorporation of expert opinion, including uncertainty, into the forecast. Our results are discussed in relation to classical time series methods and existing cohort component projections. This paper demonstrates the flexibility of the Bayesian approach to simple population forecasting and provides insights into further developments of more complicated population models that include, for example, components of demographic change

Redistribution with Sloth—Britain's problem?

SUMMARY Many if not most analyses of Britain's economic difficulties suggest that slow growth is at the heart of the problem—and an acceleration of growth the obvious cure. Past experience in Britain and in the Third World casts doubts on this. The eradication of unemployment poverty and other social problems depends as much on structural change as on growth. Economic policy, therefore, needs to be directed much more explicitly towards what is needed to restructure the British economy in the short and over the longer run. It is not even clear that aggregate growth has more than a minor part to play in the process. RESUME La redistribution paresseuse—le problème britannique? Plusieurs, sinon la plupart, des analyses des difficultés économiques britanniques placent la lenteur du développement au coeur du problème—et proposent l'accélération du développement comme remède évident. Cette théorie est mise en question par l'expérience vécue en Grande?Bretagne ainsi que dans le Tiers Monde. L'élimination du chômage, de la pauvreté et d'autres problèmes sociaux dépend autant de l'évolution structurale que de la croissance. La politique économique devrait, par conséquent, s'orienter beaucoup plus explicitement vers ce qui est nécessaire à la restructuration de l'économie britannique à courte et à longue échéance. Il n'est même pas évident que la croissance globale ait autre qu'un rôle mineur dans le processus. RESUMEN La lentitud en la redistribución, uno de los problemas principales de la Gran Bretaña de hoy Muchos, si no la mayoría de los análisis de las dificultades económicas de la Gran Bretaña, sugieren que el problema fundamental es su desarrollo demasiado lento y que la solución se halla en una aceleración del crecimiento. Esta afirmación parece ser ociosa a la vista de la experiencia pasada de la Gran Bretaña y del Tercer Mundo. La supresión del paro, la pobreza y otros problemas sociales depende tanto de los cambios estructurales como del crecimiento. La política económica, así pues, debería orientarse hacia una reestructuración de la economía británica, tanto a corto como a largo plazo. El crecimiento de conjunto no parece tener más que escasa importancia en este proceso

A biologically inspired onset and offset speech segmentation approach

A key component in the processing of speech is the division of longer input sounds into a number of smaller sections. For speech interpretation it is generally easier to classify single sections. Similarly, when processing speech for other purposes (e.g. speech filtering), it can be easier and more relevant to process individual phonemes. Here, we propose a biologically inspired speech segmentation technique that filters the speech into multiple bandpassed channels using a Gammatone filterbank, and then uses an essentially energy-based spike coding technique in order to find the onsets and offsets present in an audio signal. These onsets and offsets are then processed using leaky integrate-and-fire neurons, and the spikes from these used to determine the speech segmentation. We evaluate this new system using a quantitative evaluation metric, and the promising results of segmentation of both clean speech and speech in noise demonstrate the effectiveness of this technique

The Early Evolution of Primordial Pair-Instability Supernovae

The observational signatures of the first cosmic explosions and their chemical imprint on second-generation stars both crucially depend on how heavy elements mix within the star at the earliest stages of the blast. We present numerical simulations of the early evolution of Population III pair-instability supernovae with the new adaptive mesh refinement code CASTRO. In stark contrast to 15 - 40 Msun core-collapse primordial supernovae, we find no mixing in most 150 - 250 Msun pair-instability supernovae out to times well after breakout from the surface of the star. This may be the key to determining the mass of the progenitor of a primeval supernova, because vigorous mixing will cause emission lines from heavy metals such as Fe and Ni to appear much sooner in the light curves of core-collapse supernovae than in those of pair-instability explosions. Our results also imply that unlike low-mass Pop III supernovae, whose collective metal yields can be directly compared to the chemical abundances of extremely metal-poor stars, further detailed numerical simulations will be required to determine the nucleosynthetic imprint of very massive Pop III stars on their direct descendants.Comment: submitted to ApJ, comments welcom

Metal Cooling in Simulations of Cosmic Structure Formation

The addition of metals to any gas can significantly alter its evolution by increasing the rate of radiative cooling. In star-forming environments, enhanced cooling can potentially lead to fragmentation and the formation of low-mass stars, where metal-free gas-clouds have been shown not to fragment. Adding metal cooling to numerical simulations has traditionally required a choice between speed and accuracy. We introduce a method that uses the sophisticated chemical network of the photoionization software, Cloudy, to include radiative cooling from a complete set of metals up to atomic number 30 (Zn) that can be used with large-scale three-dimensional hydrodynamic simulations. Our method is valid over an extremely large temperature range (10 K < T < 10^8 K), up to hydrogen number densities of 10^12 cm^-3. At this density, a sphere of 1 Msun has a radius of roughly 40 AU. We implement our method in the adaptive mesh refinement (AMR) hydrodynamic/N-body code, Enzo. Using cooling rates generated with this method, we study the physical conditions that led to the transition from Population III to Population II star formation. While C, O, Fe, and Si have been previously shown to make the strongest contribution to the cooling in low-metallicity gas, we find that up to 40% of the metal cooling comes from fine-structure emission by S, when solar abundance patterns are present. At metallicities, Z > 10^-4 Zsun, regions of density and temperature exist where gas is both thermally unstable and has a cooling time less than its dynamical time. We identify these doubly unstable regions as the most inducive to fragmentation. At high redshifts, the CMB inhibits efficient cooling at low temperatures and, thus, reduces the size of the doubly unstable regions, making fragmentation more difficult.Comment: 19 pages, 12 figures, significant revision, including new figure

The Birth of a Galaxy - III. Propelling reionisation with the faintest galaxies

Starlight from galaxies plays a pivotal role throughout the process of cosmic reionisation. We present the statistics of dwarf galaxy properties at z > 7 in haloes with masses up to 10^9 solar masses, using a cosmological radiation hydrodynamics simulation that follows their buildup starting with their Population III progenitors. We find that metal-enriched star formation is not restricted to atomic cooling ($T_{\rm vir} \ge 10^4$ K) haloes, but can occur in haloes down to masses ~10^6 solar masses, especially in neutral regions. Even though these smallest galaxies only host up to 10^4 solar masses of stars, they provide nearly 30 per cent of the ionising photon budget. We find that the galaxy luminosity function flattens above M_UV ~ -12 with a number density that is unchanged at z < 10. The fraction of ionising radiation escaping into the intergalactic medium is inversely dependent on halo mass, decreasing from 50 to 5 per cent in the mass range $\log M/M_\odot = 7.0-8.5$. Using our galaxy statistics in a semi-analytic reionisation model, we find a Thomson scattering optical depth consistent with the latest Planck results, while still being consistent with the UV emissivity constraints provided by Ly$\alpha$ forest observations at z = 4-6.Comment: 21 pages, 15 figures, 4 tables. Accepted in MNRA

Effects of Rotation on the Minimum Mass of Primordial Progenitors of Pair Instability Supernovae

The issue of which stars may reach the conditions of electron/positron pair formation instability is of importance to understand the final evolution both of the first stars and of contemporary stars. The criterion to enter the pair instability regime in density and temperature is basically controlled by the mass of the oxygen core. The main sequence masses that produce a given oxygen core mass are, in turn, dependent on metallicity, mass loss, and convective and rotationally-induced mixing. We examine the evolution of massive stars to determine the minimum main sequence mass that can encounter pair-instability effects, either a pulsational pair instability (PPISN) or a full-fledged pair-instability supernova (PISN). We concentrate on zero-metallicity stars with no mass loss subject to the Schwarzschild criterion for convective instability, but also explore solar metallicity and mass loss and the Ledoux criterion. As expected, for sufficiently strong rotationally-induced mixing, the minimum main sequence mass is encountered for conditions that induce effectively homogeneous evolution such that the original mass is converted almost entirely to helium and then to oxygen. For this case, we find that the minimum main sequence mass is ~40 Msun to encounter PPISN and ~65 Msun to encounter a PISN. When mass-loss is taken into account those mass limits become ~50 Msun for PPISN and ~80 Msun for PISN progenitors. The implications of these results for the first stars and for contemporary supernovae is discussed.Comment: 23 pages, 8 figure

Key Learnings from the PEER Project. A Combined Research Paper

The inclusion of participation rights in the 1989 United Nations Convention on the Rights of the Child (UN CRC) promotes the right, independent of age, for all citizens to actively ex- press their opinion and take part in decisions regarding all aspects of their lives. The UN Committee on the Rights of the Child (UNComRC), the Council of Europe’s strategy for Building a Europe for and with Children, as well as their 2012 Recommendation on the Participation of Children and Young People Under the Age of 18 underline the importance of the right and have developed guidance on how to encourage and empower children to participate. For many children in European societies there is a growing pool of opportunities not only to take part in education, health care, entertainment, sports and culture, but also to become actors who influence such settings at strategic as well as interpersonal levels (Davey, Burke, and Shaw 2010). The extent of child and youth participation varies between countries and according to social and minority status, not all having equal chances to participate (Lundy and Stalford 2013; Lansdown 2011). According to the Youth Report 2012 (European Union 2012) data, youth who are most likely to not participate in any organizational form come from Cyprus (67%), Lithuania and Hungary (both 63%), followed by Romania (60%) (EC - DG Education and Culture 2013, 10; ECORYS 2015). Children from low social economic status families and ethnic minorities, especially Roma, have a much lower level of participation. Al- though progress has been made in some countries, Roma and Traveller children and youth are mostly overlooked, due not only to their age, but also to their social economic status and ethnic prejudices (Schuurman 2012; Sykora 2012). In countries like Romania, Bulgaria and Lithuania, many Roma children cumulate social disadvantages, such as growing up in poverty, in social and spatial marginalized areas, with limited access to good quality education, barriers to adequate health care, etc., which reduce their chances to influence formal processes and decisions that affect them. Although widely recognised as fundamental, child and youth participation rights are hardly addressed through National Roma Strategies or youth policies (Schuurman 2012). Roma minority ethnics, including children are seen as passive beneficiaries of social policies and interventions, often not tailored according to their needs or worse, built on existing stereotypes. For marginalised children and young people in particular, their right to participate and act as citizens and equal stakeholders needs to be fostered through both research and action (Larkins 2016). In this context, with funding from an EU Fundamental Rights and Citizenship grant (JUST/2013/FRAC/AG/6230), a consortium of universities, research institutions and NGOs working with Roma children and young people established a participatory action project called PEER1 (Participation and Empowerment Experiences for Roma youth). Following the Youth participation in Development Guide 1 The consortium was coordinated by Dr Prof Maria Roth (Babes- Bolyai University) and the lead researcher was Dr Cath Larkins, University of Central Lancashire. The content of this paper does not reflect the official opinion of the European Union. Responsibility for the information and views expressed in the manual lies entirely with the authors. Reproduction is authorised provided the source is acknowledged. ©European Union, 2016 (DFID-CSO Youth Working Group 2010) one of our key operating concepts was the three lens approach to youth participation: in order for services to work with children as beneficiaries, workers have to engage with them as partners and support youth to become leaders. In this research paper we describe the aims, general approach and activities of the PEER project. We outline the diverse contexts in which we worked. We then provide an over- view of the key learning from the project. We conclude that Roma children and young people, in order to exercise their right to participate as citizens, will readily engage in participation opportunities whenever they can take an informal and flexible approach to engage with them on issues that they choose and that have direct relevance to their own lives, and whenever structural, institutional and expert support is available to them

Multi-Dimensional Simulations of Pair-Instability Supernovae

We present preliminary results from multidimensional numerical studies of pair instability supernova (PSN), studying the fluid instabilities that occur in multiple spatial dimensions. We use the new radiation-hydrodynamics code, CASTRO, and introduce a new mapping procedure that defines the initial conditions for the multidimensional runs in such a way that conservation of physical quantities is guaranteed at any level of resolution.Comment: Accepted for publication in Computer Physics Communications. 3 pages. 2 fig